Crowd mechanism



June 28, 1966 F. TE N N 3,258,143

CROWD MECHANISM Filed Dec. 28, 1964 5 Sheets-Sheet l INVENTOR FRIEDRICH STEINMANN ATTORNEY F. STEINMANN CROWD MECHANISM June 28, 1966 5 Sheets-Sheet 2 Filed Dec. 28, 1964 iiillllllllllllll I INVENTOR FRIEDRICH STEINMANN AT TORNEY June 28, 1966 F. STEINMANN Filed Dec. 28, 1964 CROWD MECHANISM 33 /og.i 40

3 Sheets-Sheet 5 INVENTOR FRIEDRICH ST EINMANN A BY ATTORNEY United States Patent "ice 3,258,143 CROWD MECHANISM Friedrich Steinmann, Marion, Ohio, assignor to Bucyrus- Erie Company, South Milwaukee, Wis., a corporation of Delaware Filed Dec. 28, 1964, Ser. No. 421,450 2 Claims. (Cl. 214-135) The present invention relates to a crowd mechanism for an excavator comprising a saddle block adapted for pivotal mounting on an excavator; which saddle block has a channel to receive and support a crowd handle for reciprocating movement therein, and which supports crowd handle drive means arranged to drive said crowd handle in its axial movement.

The dipper of a power excavator is maneuvered by the simultaneous or alternative operation of two, independent, directional drive components. One component is commonly effected with hoist cables, which are wound on power driven drums in the cab and suspended over sheaves at the top of the boom. The other component is provided by a crowd mechanism in the superstructure of the excavator, which operates on the dipper handle. Sometimes the crowd mechanism is mounted on the boom to operate directly on the dipper handle, and, in the alternative, it is mounted on the A-frame to operate on a crowd handle which is connected to the end of the dipper handle. In the latter arrangement, a strut member called a stiff leg is connected at its upper end to support the joint between the crowd handle and the dipper handle, and its lower end is pivotally mounted on the revolving frame of the shovel at the base of the front leg of the A-frame. The stiff leg provides support for the knee action of the articulated crowd handle and dipper handle.

In the past, the shipper shafts of the crowd mechanism have been journaled directly in the boom, or the A-frame. Hence the shipper shaft had to be centered on the pivot point of the handle directly driven by the crowd mechanism, in order that the fixed drive means could be in constant contact with the handle. While this crowd mechanism may be satisfactory in the smaller power shovels, it becomes increasingly troublesome as it is applied to larger shovels and is wholly inadequate for a two-hundred and twenty-six cubic yard shovel.

The difficulties encountered with the prior art crowd mechanisms are particularly apparent where a rack and pinion type of drive is used. Since the shipper shafts had to be centered on the pivot of the handle, generally only two independently driven shipper shaft pinions could be used to drive the handle. As the size of the shovels increased, the power requirements for the crowd mechanism increased until it has now become impractical to attempt to deliver the necessary power through only two shipper shafts. Some means was required for increasing the number of independently driven shipper shaft pinions.

Also, the prior art crowd mechanism manifested an inherent vulnerability. Ordinarily, when the dipper is hoisted, it follows the path of an involute about the shipper shaft pinion. However, when the dipper is crowded out against the stop and then hoisted, it cannot follow the involute, but is confined to an arc. The difference must be taken up by slippage in the crowd mechanism and very large forces may be developed in the mechanism.

The present invention overcomes those difliculties, permits the use of lighter A-frames than would be required by the prior art crowd mechanism and greatly facilitates the assembly and disassembly of the crowd mechanism. These results are achieved through the use of a novel saddle block which has laterally extending tnmnions that may be journaled in the top of an A-frame or in a boom, depending upon whether the crowd mechanism is to operate on a crowd handle or a dipper handle. The novel sad- 3,258,143 Patented June 28, 1966 die block contains a channel through which the handle to be driven slides, and journaled in the saddle block are two or more rollers on which the handle is supported. This saddle block supports the entire drive means for the crowd mechanism. In addition, the structural strength of this saddle block is greatly enhanced over corresponding structure known to the prior art.

Since the drive means, including the shipper shafts, pivot with the handle about the trunnions on the saddle block, the shipper shafts no longer need to be centered at the pivot point, and hence as many shipper shafts as desired may be journaled in tandem in the saddle block. The. freedom provided by the present invention, to use any number of drive sources, not only opens the way for the construction of larger shovels, but it permits safety power factors to be built into all shovels, so that a malfunction of one drive source does not cripple the entire crowd mechanism. The problems encountered in boom mounted mechanisms in the prior art are obviated by this new crowd mechanism, since the crowd machinery is no longer mounted directly in the boom but on the new, strengthened saddle block. Finally, since the crowd mechanism is a self-contained unit, its initial. assembly in the power shovel is greatly facilitated, and disassembly for repairs is made much easier.

Accordingly, it is an object of the present invention to provide a crowd mechanism which canbe built to contain any desired number of idependently driven shipper shafts.

It is another object of the present invention to provide a crowd mechanism which is a self-contained unit.

It is another object of the present invention to provide a stronger saddle block.

It is another object of the present invention to provide a crowd mechanism capable of supplying the crowd drive power required by the largest power shovels.

It is another object of the present invention to provide a crowd mechanism with a built-in power safety factor.

It is another object of the present invention to provide a crowd mechanism which may be assembled in a power shovel with greater ease.

It is another object of the present invention to provide a crowd mechanism of greater durability and reliability than the prior art devices.

It is another object of the present invention to provide a crowd mechanism that may be repaired and maintained with comparative ease and less shut-down time.

It is another object of the present invention to provide a crowd mechanism whereby the crowd machinery is not mounted directly on the superstructure of an excavator, but may move relative to the superstructure in its normal operation.

The foregoing and other objects and advantages are explicated in the description to follow. In that description, the accompanying drawings, which are a part of this disclosure, are referred to as illustrative of a specific em bodiment practicing this invention. That embodiment,

which represents the best mode contemplated by the in-v ventor of carrying out the invention, is described in sufficiently full, clear, concise and exact terms to enable any person skilled in the art to which it pertains to practice the invention. However, the embodiment described is not to be construed as the exclusive mode of carrying out the invention, for many structural changes may be made in the embodiment disclosed without advancing beyond the scope of the invention. What is regarded as the invention in its full scope is particularly pointed out and distinctly claimed in the several numbered claims at the conclusion of this specification.

In the drawings: FIG. 1 is a side view in elevation of a power shovel employing a crowd mechanism of the present invention,

FIG. 2 is a 'side view in elevation of a crowd mecha- 3 nism of the present invention with portions broken away along the lines 2 -2 in FIG. 3 and FIG. 4 to reveal certain working elements,

FIG. 3 is a top plan view of a crowd mechanism of the present invention partially in section along the line 33 in FIG. 2,

FIG. 4 is an end view in section taken along the line 44 in FIG. 3, and

FIG. 5 is an isometric representation of the saddle block in the crowd mechanism illustrated in FIGS. 2, 3 and 4.

The power shovel shown in FIG. 1 is built around a revolving frame 1 which is rotatably mounted on a base 2. The base 2 is supported upon four crawler tractors 3, one at each corner, by means of an automatically levelling, hydraulic jack suspension system. The revolving frame 1 supports a cab 4 containing the drive motors and associated mechanism for operating the shovel, and provides a base for a superstructure.

The superstructure mounted on the revolving frame 1 includes a vertically rising A-frame 5 and a boom 6 which angles forward and upward from its pivotal mounting at the front end of the revolving frame 1. Boom support cables 7 are strung from the top of the boom 6 to the top of the A-frame 5 to support the top of the boom 6. A crowd mechanism 8 is pivotally mounted on trunnions 9 journaled in the top of the A-frame 5, and a crowd handle 10 is supported through and driven by the crowd mechanism 8. The front end of the crowd handle 10 is pivotally articulated in a joint 11 with a back end of a dipper handle 12, which has a dipper 13 on its front end. The joint 11 connecting the crowd handle 10 and the dipper handle 12 is supported on a pivotal bearing on the top of a stiff leg 14, which is pivotally supported at its bottom end on a mounting on the front of the revolving frame 1 next to the front legs of the A-frame 5. The dipper 13 is suspended from a bail 15 on a dipper sheave block 16, which is hung on hoist tackle 17 about a boom sheave block 18 at the top of the boom 6. A hoist line 19 connects the hoist tackle 17 over the boom sheave block 18 and a sheave 20 mounted in the top of the A-frame 5 to a hoist drive (not shown) in the cab 4. An operators cab 21 projects from the front of the revolving frame 1 to house the controls and operator of the power shovel. A jib crane 22 is permanently mounted on a platform 23 on top of the A-frame for use in assembling or disassembly of the elements of the superstructure and a platform 24 is built on the top of the boom 6 to serve a similar purpose.

An accurate picture of the power shovel shown in FIG. 1 is not complete without some comparison for estimating its size, and for lack of a more graphic standard of comparison, recitation of a few dimensions may serve the purpose. From the center of rotation of the revolving frame 1, which is at the center of the shaft shown to project from the center of the bottom of the base 2, to the back of the revolving frame 1 measures ninety-four feet, and the center of rotation is about forty feet from the front of the revolving frame 1. The bottom of the operators cab 21 is over fifty feet from the surface on which the crawler tractors 3 rest. The maintenance and assembly paltform 24 on the top of the boom 6 is two hundred fifty feet above the surface supporting the tractors 3, and about seventy-five feet above the maintenance platform 23 on the top of the A-frame 5. The dipper 13, in the position shown, extends about two hundred fifty feet in front of the center of rotation, and it is designed for a capacity of 226 cubic yards, the top of the teeth projecting over thirty feet above the bottom of the dipper 13. The pairs of tractors 3 span about one hundred feet from front to back, and side to side (not shown).

The central component of the crowd mechanism 8 is a saddle block 25 shown in FIG. 5. The saddle block 25 has a closed ring yoke 26 as an external supporting frame extending around it at its center and the mounting trunnions 9 project laterally from the sides of the ring yoke 26. L-shaped shipper shaft bearing supports 28 project laterally from adjacent the bottom at each end of the saddle block 25 and extend longitudinally to the ring yoke 26. Tunneled longitudinally through the center of the saddle block 25 is a crowd handle channel 29 through which the crowd handle 10 is mounted. Projecting from each end of the saddle block 25 beneath the lateral walls of the crowd handle channel 29 are roller bearing supports 30.

The remaining structure of the crowd mechanism is shown in FIGS. 24. The crowd handle 10 is shown mounted in the crowd handle channel 29 and it is supported on rollers 31 mounted on shafts at each end of the crowd handle channel 29 which are journaled in antifriction bearings in the roller bearing supports 30. Twin racks 32 are shown afiixed to the bottom of the crowd handle 10. Four crowd drive motors 33 are mounted on top of the saddle block 25, and each of these is connected through a gear train to drive one shipper shaft 34 having a shipper shaft pinion 35 mounted on it to engage one of the twin racks 32 on the crowd handle 10.

Each of the gear trains connecting the crowd drive motors 33 to the shipper shafts 34 is mounted in a gear housing 36. Since the gear trains are identical for each crowd drive motor 33, it will suifice to describe one of them at random with the understanding that the description applies equally to all. A motor gear 37 is mounted on an extension shaft 38 which is journaled in antifriction bearings in the gear housing and joined to a shaft 39 of the motor 33 with a flanged coupling 40. The motor gear 37 drives a first intermediate gear 41 on a first intermediate shaft 42 along with a first intermediate pinion 43. The first intermediate shaft 42 is mounted in antifriction bearings in the gear housing 36. The first intermediate pinion 43 engages and drives a second intermediate gear 44 which is mounted on a second intermediate shaft 45 journaled in antifriction hearings in the gear housing 36. Also mounted on the second intermediate shaft 45 is a second intermediate pinion 46 which engages and drives a shipper shaft gear 47 on the shipper shaft 34. Although it is advisable to mount the faster rotating shafts in antifriction bearings, sleeve bearings have been found to be adequate for mounting the slow moving shipper shafts 34 in the shipper shaft bearing supports 28 and the walls of the saddle block 25.

Regarding the construction of the various components, the saddle block 25 may be of hollow construction fabricated from structural steel or it may be a steel casting. In the embodiment shown, the saddle block 25 is thirty feet long, over nineteen wide, as measured from the outside of the shipper shaft bearing supports 30, and over nineteen feet high as measured from the top to the bottom of the ring yoke 26. The type of gears used is optional within the requirements of the particular application, spur teeth may be used on the gears and pinions, and in fact the racks 32 on the crowd handle 10 and the meshing shipper shaft pinion 35 have spur teeth, but helical teeth provide quieter operation and hence all of the other faster rotating gears and pinions have helical teeth.

In the power shovel shown in FIG. 1 embodying the present invention, the boom 6 and the A-frame 5 are double element structures, the two spaced halves of the boom 6 and A-frame 5 being joined together to function as a unit and having the dipper handle 12, the crowd mechanism 8 and crowd handle 10 mounted between them. Accordingly, there are two sets of boom support cables 7, hoist lines 19, A-frame hoist sheaves 20, boom sheave blocks 18, hoist tackle 17, and dipper sheave blocks 16, one for each half of the double A-frame 5 and double boom 6. The crowd mechanism 8, with the crowd handle 10 supported on the rollers 31 in the crowd handle channel 29 of the saddle block 25, is mounted in the top I of the A-frame 5 on the trunnions 9 projecting laterally from the saddle block and journaled in the A-frame 5 members.

When the drive motors 33 are run in one direction, the shipper shaft 34 rotates in the opposite direction and at a speed greatly reduced by the gear train. All of the drive motors, of course, operate simultaneously though mechanically independently to drive the shipper shafts 34 independently and simultaneously. The shipper shaft pinions 35, on the shipper shafts 34 engage the twin racks 32 on the crowd handle 10 to drive the crowd handle 10 forward. When the drive motors 33 operate to move the crowd handle 10 forward, the crowd handle 10 drives the dipper handle 12 forward. However, the movement of the dipper handle 12 is not linear with respect to the movement of the crowd handle 10 due to the knee action or toggle type of crowd mechanism resulting as the joint 11, joining the dipper handle 12 and the crowd handle 10, moves through an arc defined by the rotation of the stiff leg 14 as a radius about its pivotal mounting on the revolving frame 1. Hence, a mechanical power advantage is achieved with the knee action mechanism, depending upon the angle between the crowd handle 10 and the dipper handle 12. In some applications, however, it is desirable to omit the crowd handle 10 and the stiff leg 14, and mount the crowd mechanism 8 on the boom 6 to operate directly upon the dipper handle 12, eliminating the mechanical effects of the toggle. In such an application, the twin racks 32 would be mounted on the dipper handle 12, which would be supported in the crowd handle channel 29 just as the crowd handle 10 is in the embodiment shown. Since the embodiment shown here has the knee action type of crowd, a distinction in terminology is made between the crowd handle 10 and the dipper handle 12, but in the claims that follow the term crowd handle is to be understood in a broader sense. The term crowd handle is to be understood to mean any member acted upon directly by the crowd drive means (including the gear train or other transmission that might be used) whether or not that crowd handle may also serve as a dipper handle or some other member.

When the drive motors 33 are reversed, the shipper shaft pinion is reversed and the crowd handle 10 is retracted. As the crowd handle 10 is retracted from the extended position shown in FIG. 1, it draws the join-t 11 backward and upward through its arc of travel. It is apparent that due to the arc of travel of the joint 11 at the top of the stiff leg 14, the crowd mechanism 8 pivots on the trunnions 9 from the inclined attitude shown to a horizontal position when the crowd handle 10 is retracted. Similar but greater pivotal movement would be necessary if the crowd mechanism 8 were mounted on the boom 6 to operate directly on the dipper handle 12 since then it would be subjected also to the vertical movement of the dipper 13 suspended on the hoist tackle 17.

If the crowd drive mechanism, comprising the drive motors 33, gear train and pinion shafts 34 were mounted directly in the boom 6 or A-frame 5, as is done in the prior art, it is evident that the shipper shaft would have to be mounted where the trunnions 9 of the described embodiment of the present invention are mounted to allow for the necessary pivotal movement of the crowd handle 10 or dipper handle 12. If more than one shipper shaft were used, all of the shipper shafts would have to be concentric on the pivot point, and hence no more than two shipper shafts could be used without involving prohibitively complex drive means. Since the entire crowd mechanism 8 of the present invention is mounted independently of the A-frame 5 or boom 6, it pivots as a unit with the handle it operates on. Hence, the problem of a shipper shaft rotating against a dipper stop is obviated. Also, any number of independently driven shipper shafts may be mounted in tandem.

The use of parallel twin racks 32, each engaging independently driven shipper shaft pinions 35, has been found from experience to be advisable. Both the crowd handle 10 and the dipper handle 12 swing slightly from side to side in the course of normal operation. If a single row of shipper shaft poinions 35 were used, or if the pairs of shipper shaft pinions 35 were driven in common from a single shipper shaft 34, the full force of the crowd mechanism 8, as a result of the swinging of the crowd handle 10, would bear first on one side of the shipper shaft pinions 35 and the rack 32 and then on the other side. Since only a small area would receive the full crowd force under those circumstances, a tremendous pressure could be brought to bear against the edges of the teeth on the rack and pinions, resulting in excessive wear, and often in breakage. By using a pair of independently driven shipper shaft pinions 35 acting on parallel twin racks 32, the force is substantially evenly distributed across the teeth of the pinions 35 and the rack 32.

Although the embodiment shown utilizes only four drive means, each of which includes the motors 33 with associated gear trains and shipper shafts 34 and shipper shaft pinions 35, any number might be used as is required to produce the necessary force. The total crowd force or load may thus be distributed evenly over any number of independent drive means. As a result of this even distribution of the load, greater efficiency is achieved. Moreover, this distribution of the crowd load permits a powersafety factor to be built into any crowd mechanism 8 to that if there is a malfunction in any one, or perhaps more, of the drive means, the malfunctioning drive means could be repaired without interrupting the operation of the crowd mechanism 8. The distribution of the load over many independent drives also obviates numerous other difficulties encountered when the entire load must fall on one or two drives.

The present invention also provides a saddle block which is superior to the prior art in many respects. The saddle block 25 of the present invention has superior structural strength as a result of its closed crowd handle channel 29 and ring yoke 26 which are not vulnerable to spreading or being skewed out of alignment. Also, the saddle block 25 contains support means for the crowd handle 10 in the form of the rollers 31 so that th crowd handle 10 no longer needs to be supported on shrouds on the shipper shaft pinions. This permits the use of machined shipper shaft pinions, and removes the weight of the crowd handle from the shipper shaft pinion. Although in the embodiment of the drawings no top stabilizing means for the crowd handle 10 are shown in the saddle block 25, one skilled in the .art will appreciate the possibility of adding a slide plate or toproller bearing on the top of the crowd handle 10, where desired. Also, in the embodiment described, the laterally extending trunnions 9 are used to provide a pivotal mounting means for the saddle block 25, but of course many equivalent structures may be used to achieve the same result in the same way, and the possibility of using a shaft fixed in the, superstructure of the excavator and journaled through the saddle block 25 comes to mind immediately as one such equivalent, and these equivalents are intended to be included in the meaning of the word trunnion here.

Many variations in the structure of the preferred embodiment disclosed here in addition to those already mentioned are possible within the scope of the present invention. For example, a worm drive might be used in place of the gear train shown; the rack 32 may be mounted on the side of the crowd handle 10 or additional racks 32 may be added, with appropriate modifications in the remainder of the crowd mechanism; the gear drive shown may be replaced with a rope drive or a friction drive; other forms of motive power may be substituted for the drive motors 33 shown; other support means for the crowd handle 10 may replace the rollers 31 shown; and numerous other variations may also be possible. Also, while the r initial application of the invention is in a power shovel,

In a crowd mechanism for a power shovel, the combination comprising:

a saddle block mounted on said power shovel for pivotal movement about a transverse axis, having a crowd handle channel extending longitudinally therethrough, and having a crowd handle support roller rotatably mounted in the bottom of said crowd handle channel; crowd handle nonrotatably mounted through said crowd handle channel to be supported for axial movement upon said crowd handle support roller, and having an axially extended rack fastened to said crowd handle;

plurality of crowd hand-1e drive motors mounted said saddle block;

plurality of shipper shafts journaled transversely in said saddle block, having pinions mounted thereon for engagement with said rack, and having gears mounted thereon to receive driving power; and

a plurality of transmission means for independently proa dipper stick having a dipper at one end supported on a hoist line anchored to a hoist drive on said revolving frame and supported on sheaves at the top of said A-frame and said boom, and having its other end pivotally supported on a pivotally mounted stiff leg extending upward from said revolving frame;

a crowd mechanism having a saddle block rotatably mounted on laterally extending trunnions journaled in the top of said A-frame, said saddle block having a crowd handle channel extending longitudinally through it with roller supports across the bottom of said channel journaled in said saddle block;

a crowd handle mounted in said crowd handle channel in said saddle block, having one end pivotally fastened to said end of said dipper handle supported on said stiff leg, and having a drive rack fastened to it and extending longitudinally of it;

and said crowd mechanism including a plurality of crowd handle drive motors mounted on said saddle block, and a plurality of shipper shafts journaled in said saddle block with a gear chain connecting each of said shipper shafts to be individually driven by said drive motors and a pinion mounted on each of said shipper shafts and engaging said rack on said crowd handle to transmit motive power from said drive motors to said crowd handle.

References Cited by the Examiner UNITED STATES PATENTS 1,526,830 2/1925 Byrne 214-135 X 2,315,781 4/1943 Gerow 2l4135 X 3,004,674 10/1961 Grilfith 214135 X HUGO O. SCHULZ, Primary Examiner. 

2. A POWER SHOVEL COMPRISING THE COMBINATION OF A REVOLVING FRAME MOUNTED ON A BASE, AND HAVING AN A-FRAME MOUNTED THEREON ABOVE SAID BASE, AND A BOOM PROJECTING UPWARDLY FROM A PIVOTAL MOUNTING AT THE FRONT OF SAID REVOLVING FRAME AND SUPPORTED AT THE TOP ON BOOM SUPPORT CABLES TIED TO THE TOP OF SAID A-FRAME; A DIPPER STICK HAVING A DIPPER AT ONE END SUPPORTED ON A HOIST LINE ANCHORED TO A HOIST DRIVE ON SAID REVOLVING FRAME AND SUPPORTED ON SHEAVES AT THE TOP OF SAID A-FRAME AND SAID BOOMS, AND HAVING ITS OTHER END PIVOTALLY SUPPORTED ON A PIVOTALLY MOUNTED STIFF LEG EXTENDING UPWARD FROM SAID REVOLVING FRAME; A CROWD MECHANISM HAVING A SADDLE BLOCK ROTATABLY MOUNTED ON LATERALLY EXTENDING TRUNNIONS JOURNALED IN THE TOP OF SAID A-FRAME, SAID SADDLE BLOCK HAVING A CROWD HANDLE CHANNEL EXTENDING LONGITUDINALLY THROUGH IT WITH ROLLER SUPPORTS ACROSS THE BOTTOM OF SAID CHANNEL JOURNALED IN SAID SADDLE BLOCK; A CROWD HANDLE MOUNTED IN SAID CROWD HANDLE CHANNEL IN SAID SADDLE BLOCK, HAVING ONE END PIVOTALLY FASTENED TO SAID END OF SAID DIPPER HANDLE SUPPORTED ON SAID STIFF LEG, AND HAVING A DRIVE RACK FASTENED TO IT AND EXTENDING LONGITUDINALLY OF IT; AND SAID CROWD MECHANISM INCLUDING A PLURALITY OF CROWD HANDLE DRIVE MOTORS MOUNTED ON SAID SADDLE BLOCK, AND A PLURALITY OF SHIPPER SHAFTS JOURNALED IN SAID SADDLE BLOCK WITH A GEAR CHAIN CONNECTING EACH OF SAID SHIPPER SHAFTS TO BE INDIVIDUALLY DRIVEN BY SAID DRIVE MOTORS AND A PINION MOUNTED ON EACH OF SAID SHIPPER SHAFTS AND ENGAGING SAID RACK ON SAID CROWD HANDLE TO TRANSMIT MOTIVE POWER FROM SAID DRIVE MOTORS TO SAID CROWD HANDLE. 